title: Increased production of aflatoxins by Aspergillus parasiticus Speare in the presence of rubratoxin B.
abstract: The influence of rubratoxin B, a metabolite of Penicillium rubrum Stoll, on the growth and aflatoxin production of a strain of Aspergillus parasiticus Speare grown in the chemically defined medium of Reddy et al. (Appl. Microbiol. 22:393-396, 1971) was studied. After 4 days of incubation on a rotary shaker at 25 degrees C, the presence of 10 microgram/ml caused 45 to 50% reduction in dry weight production, although at the same concentration of rubratoxin B, the reduction of growth after 10 days was only 15%. In the presence of 50 microgram/ml there was a reduction in dry weight production of 94% after 4 days of incubation, and it was still 86% after 8 days. Rubratoxin B concentrations of 50 microgram/ml and higher usually caused a reduction in aflatoxin production in the medium comparable with the reduction in biomass, but at concentrations as low as 10 microgram/ml, there was a pronounced increase in the production of aflatoxins, especially of G1, despite the reduction in biomass. The ecological significance of these observations is discussed.
mesh_terms: D016604:Aflatoxin B1; D000348:Aflatoxins / Q000096:biosynthesis*; D001230:Aspergillus / Q000187:drug effects / Q000254:growth & development*; D009183:Mycotoxins / Q000494:pharmacology*
chemical_list: D000348:Aflatoxins; D009183:Mycotoxins; C027955:aflatoxin G1; D016604:Aflatoxin B1